In the art of automatically applying axial lead electrical components to a printed circuit board, which is well known in the industry, the components are usually supplied to the insertion head of the machine in a desired sequence for insertion through the board. The components are supplied on a reel in which the component axial leads are taped on their outer extremities to present the components in a taped series to the insertion head. The insertion tooling contains a mechanism to sever the component leads from the tape, form the leads at a right angle to the component body, and insert the leads into pre-selected openings in the board. Thereafter, a cut-clinch mechanism cuts and forms the leads protruding through the board undersurface to lock the component to the board. Insertion heads of this type are disclosed in U.S. Pat. No. Re 27,968.
In the operation of these heads, there is a pair of vertically driven insertion tooling assemblies which travel from a position to receive the component from the taped input to a position to insert the component leads into the openings in the board. The mechanism to vertically reciprocate the insertion tooling has, in the past, been a pneumatic cylinder arrangement (such as illustrated in U.S. Pat. No. 27,968) which drives a linkage causing the placement head to move up and down or a servo driven lead screw (such as illustrated in U.S. Pat. No. 4,719,810).
In addition to the above considerations, during the insertion sequence of axial lead components (e.g., resistors, diodes, etc.) it is also desirable to provide for the insertion of the leads of the components at varying center distances. Accordingly, variable center distance (VCD) component insertion machines have been developed. In such machines, two insertion tooling assemblies (one for each lead) are simultaneously driven to sever the leads from the tape, form the leads and insert the leads into pre-selected openings in the board. The insertion toolings are laterally moveable so that the center distance between the insertion toolings may be varied to accommodate different insertion center distances.
One disadvantage of the prior art VCD insertion heads is that they employed a large mass of complicated pneumatic crank arms or lead screw mechanisms to drive the insertion heads up and down. They, therefore, were difficult to control or operate at high rates of insertions per hour.